I stumbled across this today, shows an odd attempt at treating rear corners.
Do not follow this example as I think it leaves a lot on the table, but better than nothing.
https://www.cherokeeforum.com/f46/ec...241367/index2/
From that same thread, I think the below if can work on a boxy body can work on a boxy cab.
by
mannydantyla
https://www.cherokeeforum.com/f46/ec...241367/index3/
EDIT:
Good pick up truck cab thread
flow separation:Tiger Woods meets Cinderella,or 5-seconds to a perfect roofline
https://ecomodder.com/forum/showthre...ds-2104-2.html